A drain current model is developed for a symmetrically driven undoped (or lightly doped) symmetric double-gate MOSFET (SDGFET) under the drift-diffusion transport mechanism, with velocity saturation effects being included as an integral part of the model derivation. Velocity saturation effects are modeled by using the Caughey-Thomas engineering model with exponent n = 2. Id-Vd, Id-Vg, gm -Vg, and gDS-Vd comparisons are made with 2-D device simulation results, and a very good match is found all the way from subthreshold to strong inversion. Gummel symmetry compliance is also shown.